Load cells are special cases of the force transducers or pick ups, and are provided for the construction of weighing devices. Such weighing devices are often also used in the supply of foodstuffs, so that they often must satisfy special hygiene regulations. Therefore, it is also necessary for the load cells used in those applications, that these are constructed so that no dirt and no foodstuff residues can permanently collect on their surfaces, or at least must be easily removable. Furthermore, there are often horizontal surfaces, gaps and depressions on such load cells, which are hardly accessible and therefore can only be cleaned with difficulty, where then bacteria, viruses and fungi easily deposit and take hold. Therefore, in the use of load cells in many areas of the chemical, pharmaceutical, cosmetic, and foodstuff industries, it is necessary that these are easy to clean and if possible have no surface areas on which dirt, foodstuff residues, chemicals, bacteria, viruses and fungi can become deposited and take hold, penetrate, or build-up.
A hermetically sealed measured value pick-up or transducer, which represents a load cell, is known from the DE 10 2004 047 508 B3, which is embodied as a horizontally installable bending beam. This bending beam consists of a force introduction or input part and a force output part, between which a force measuring element is arranged. In that regard, the force measuring element consists of a vertical bending spring, which was produced by two oppositely directed horizontal transverse bored holes in the middle bending beam part, and on which strain gages are applied on both sides as shear force pick-ups or transducers, which produce a proportional electrical signal in connection with a weight loading. For the hermetic sealing in that regard, pot-shaped metallic sheet metal parts are welded into the bored holes, and hermetically tightly enclose the sensitive electrical measuring elements. Thereby it is primarily prevented, that moisture and other corrosive dirt particles come into contact with the sensitive measuring elements, so that a load cell having a long life is produced. While this load cell is rod shaped and equipped with largely flat exterior surfaces, whereby however foodstuff or liquid residues can deposit especially on the horizontally extending cover surface, and these residues in connection with moisture tend to cause an increase or multiplication of bacteria or viruses. Moreover, dirt and foodstuff components could also adhere in the pot-shaped depressions, which may only be cleaned with difficulty, and in which fungi and bacteria could form. Therefore, even such a hermetically sealed load cell is often not usable in aseptic areas or fields according to the applicable hygiene regulations.
From the German patent publication DE 37 15 572 A1, a load cell for an electromechanical platform scale is known, which essentially consists of a cylindrical round rod, from which at least flowable foodstuffs and liquids would run-off by means of gravity. In that regard, one side of the bending rod is secured by means of two screws on the scale housing, while the opposite end as a flattened round rod is connected with the weighing platform, whereby the weight force is introducible transversely to the longitudinal direction. However, in this load cell, the strain gages may be applied on the surface of the bending rod for producing the electrical measurement signals, so that such a load cell cannot be cleaned with watery or aqueous cleaning agents, and therefore is not always usable in the foodstuff industry or in aseptic areas or fields.
A further load cell with cylinder-shaped horizontally arranged housing is known from the German patent publication DE 28 18 140 A1, which is to be completely protected with respect to foreign influences. In that regard, a horizontal round rod is arranged in the housing body, and is secured at its one end region in a free carrying pipe. On the outer circumferential surface of the free carrying pipe, strain gages are applied, which pick-up and measure a strain on the outer circumferential surface of the pipe in connection with a vertical force introduction into the end point of the rod. In that regard, the free carrying pipe is hermetically tightly enclosed by a cylinder-shaped enclosure sleeve as a housing part. However, the force introduction is carried out via a threaded bolt in a chamber that is open at least toward the bottom, and in which a force introduction eye grasps around the rod, which is movably guided in this open chamber. Because this chamber is not hermetically enclosed, dirt and liquid residues can penetrate therein and are hardly removable, so that this load cell is not usable in contact with foodstuffs.
An installation or mounting set for a load cell is previously known from the European patent publication EP 1 698 871 A1, and is especially usable in the area or field of the chemical and pharmaceutical, the foodstuff and cosmetic industry. In that regard, this installation or mounting set includes a vertically arranged load cell, which is arranged between two parallel horizontally arranged mounting plates. Apparently, two round compression parts are provided as force introduction or input and force output elements, between which the load cell is arranged. In that regard, the load cell is arranged enclosed in a round conically extending housing, which engages into the compression parts or encompasses these so that this installation or mounting set is well cleanable and apparently has few gaps and hollow spaces in which bacteria, viruses and fungi could form. However, hereby the compression parts as force introduction or force output elements are only loosely connected with the load cell, so that such a load cell can only be installed vertically and also cannot be connected securely with the scale, so that another installation or mounting set will always additionally be necessary.